Patterning material including silicon-containing layer and method for semiconductor device fabrication

ABSTRACT

In one exemplary aspect, the present disclosure is directed to a method for lithography patterning. The method includes providing a substrate and forming a target layer over the substrate. A patterning layer is formed by depositing a first layer having an organic composition; depositing a second layer including over 50 atomic percent of silicon; and depositing a photosensitive layer on the second layer. In some implementations, the second layer is deposited by ALD, CVD, or PVD processes.

PRIORITY

This application is a continuation application of U.S. patentapplication Ser. No. 17/213,723, filed Mar. 26, 2021, issuing as U.S.Pat. No. 11,715,640, which claims priority to provisional application63/085,519, filed Sep. 30, 2020, which are hereby incorporated byreference in their entireties.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experiencedexponential growth. Technological advances in IC materials and designhave produced generations of ICs where each generation has smaller andmore complex circuits than the previous generation. In the course of ICevolution, functional density (i.e., the number of interconnecteddevices per chip area) has generally increased while geometry size(i.e., the smallest component (or line) that can be created using afabrication process) has decreased. This scaling down process generallyprovides benefits by increasing production efficiency and loweringassociated costs. Such scaling down has also increased the complexity ofprocessing and manufacturing ICs.

As semiconductor fabrication processes desire smaller process windows,the spacing desired between elements (i.e., the pitch) of a devicedecreases and becomes more and more difficult to achieve usingtraditional optical masks and photolithography equipment. Advancementsin photolithography tools can assist in meeting the scaled downprocesses. For example, extreme ultraviolet (EUV) lithography andimmersion lithography have been utilized to support critical dimension(CD) requirements of smaller devices. Additionally, patterning methodsthemselves have developed to drive formation of features of the desiredCD below that of the capability of the lithography equipment itself.While the lithography equipment and patterning advances have beensuitable in many respects, further advancements are desirable.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 illustrates a flow chart of an embodiment of a lithographypatterning method according to various aspects of the presentdisclosure.

FIGS. 2, 3, 4, 5, 6, 7, 8, 9, 10 11, 12, 13, 14, 15 and 16 providecross-sectional views of an example device 200 aspects of which arefabricated according to the method of FIG. 1 ;

FIG. 17 provides a cross-sectional view of another example device havingan adhesion layer and having aspects of which are fabricated accordingto the method of FIG. 1 ;

FIG. 18 provides a cross-sectional view of another example device havinga patterned layer and having aspects of which are fabricated accordingto the method of FIG. 1 ;

FIGS. 19, 20A, 20B, 21A, 21B, 22, 23A, 23B, 24A, 24B, 25A, 25B, 26A,26B, 27A, 27B, 28A, 28B, 29A, and 29B provide cross-sectional views ofan example device 1900 aspects of which are fabricated according to themethod of FIG. 1 ;

FIG. 30 provides a schematic illustration of a portion deposition toolthat may be used according to various aspects of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

As the pitch of elements of semiconductor devices continue to decreaseand dimensions of features continue to shrink, improvements inpatterning methods and materials are desired for providing high quality,increased pattern density, and decreased critical dimension (CD)devices. The present disclosure provides for material compositions,material stacks, and methods of implementing said compositions andstacks that can, in some implementations, improve patterning metricsincluding line width roughness (LWR) and local critical dimensionuniformity (LCDU). In some embodiments, the improvements drive theformation of materials using compositions and/or deposition methods thatproduce high density materials, increased hardness of materials,improved elastic modulus of materials, and/or high etch selectivity ofmaterials that are used in one or more aspects of patterning. Theseproperties alone or in combination can improve LWR and LCDU.

One feature of semiconductor devices for which aggressive dimension andpitch requirements are being implemented is the back-end-of-the-line(BEOL) features. The BEOL features include those wiring or metallizationlayers providing an interconnection between individual devices of asubstrate. In some embodiments, trenches or via openings are patternedinto a dielectric layer. By controlling the configuration of thetrenches and via openings, a routing of the interconnection of devicesis provided when the trenches or openings are subsequently filled withconductive material.

Referring to FIG. 1 , illustrated is a method 100 of patterning a layer.The method 100 may be used to pattern a layer of a semiconductor device.The semiconductor device may include SRAM and/or other logic circuits,passive components or active microelectronic devices, such as resistors,capacitors, inductors, diodes, p-type field effect transistors (PFETs),n-type field effect transistors (NFETs), metal-oxide semiconductor fieldeffect transistors (MOSFETs), CMOS transistors, bipolar junctiontransistors (BJTs), laterally diffused MOS (LDMOS) transistors, highvoltage transistors, high frequency transistors, other suitablecomponents, or combinations thereof. Exemplary NFETs and PFETs includemulti-gate devices such as fin type field effect transistors (FinFET),gate-all-around (GAA) devices, and/or other suitable device types. Thesemiconductor device can be included in a microprocessor, a memory,and/or other IC device. In some embodiments, the semiconductor device isa portion of an IC chip, a system on chip (SoC), or portion thereof.

The method 100 may be implemented, in whole or in part, by a systememploying deep ultraviolet (DUV) lithography, extreme ultraviolet (EUV)lithography, electron beam (e-beam) lithography, x-ray lithography, andother lithography processes to improve pattern dimension accuracy. In anembodiment, EUV lithography is used to provide an aggressivedimension/pitch of the patterned layer. Additional operations can beprovided before, during, and after the method 100, and some operationsdescribed can be replaced, eliminated, or moved around for additionalembodiments of the method. The method 100 is an example and is notintended to limit the present disclosure beyond what is explicitlyrecited in the claims. The method 100 is described below in conjunctionwith FIGS. 2-16 .

The method 100 begins at block 102 where a target layer or layers areprovided for patterning. The target layer is any layer or layers forwhich patterning is desired. By patterning the target layer(s), thetarget layer(s) are configured into a plurality of features, comprisedof the target layer, having openings interposing the features. Thepattern may be directed to various semiconductor device features such asinterconnect lines, gate structures, isolation structures, activeregions, and the like. In some embodiments, the target layer pattern isprovided below the resolution limit of the lithography equipment due tothe patterning methods such as multiple-patterning techniques.

In some implementations, the target layer(s) is provided over asemiconductor structure. The semiconductor structure includes asemiconductor substrate and, in some implementations, various layers orfeatures disposed on the semiconductor substrate. In an embodiment, thesemiconductor substrate includes silicon. Alternatively or additionally,substrate includes another elementary semiconductor, such as germanium;a compound semiconductor, such as silicon carbide, gallium arsenide,gallium phosphide, indium phosphide, indium arsenide, and/or indiumantimonide; an alloy semiconductor, such as silicon germanium (SiGe),GaAsP, AlInAs, AlGaAs, GaInAs, GaInP, and/or GaInAsP; or combinationsthereof. Alternatively, substrate is a semiconductor-on-insulatorsubstrate, such as a silicon-on-insulator (SOI) substrate, a silicongermanium-on-insulator (SGOI) substrate, or a germanium-on-insulator(GOI) substrate. Semiconductor-on-insulator substrates can be fabricatedusing separation by implantation of oxygen (SIMOX), wafer bonding,and/or other suitable methods. Within or upon the substrate, there maybe various features associated with the semiconductor devices. Thefeatures may include transistor features such as gate structures andsource/drain regions; isolation features; interconnect features such asmetallization layers and vias; and/or other features.

As but one example, a semiconductor structure 202 is illustrated in FIG.2 . The semiconductor structure 202 includes a base substrate 201 havinga plurality of active devices 203 formed thereon. The devices asillustrated include gate structures 205 and source/drain features 207having interposing isolation features 209. A multi-layer interconnect(MLI) 213 is formed over the devices 203. The MLI 213 may include adielectric layer 211 formed over the devices and an illustrative contact215 extending to the source/drain feature 207. The MLI 213 includesvarious other metallization layers, vertically extending vias, andinterposing isolation layers that connect various features of thedevices 203 as discussed below.

The gate 205 is configured to achieve desired functionality according todesign requirements of associated device, for example, providing ap-type work function or n-type work function. The gate 205 may include agate dielectric layer and a gate electrode (for example, a work functionlayer and a bulk conductive layer). Gate structures 205 may includenumerous other layers, for example, capping layers, interface layers,diffusion layers, barrier layers, hard mask layers, or combinationsthereof.

Gate dielectric layer(s) of the gate structure may include a high-kdielectric layer, which includes a high-k dielectric material, whichrefers to a dielectric material having a dielectric constant that isgreater than that of silicon dioxide (k≈3.9). For example, the high-kdielectric layer includes HfO₂, HfSiO, HfSiO₄, HfSiON, HfLaO, HfTaO,HfTiO, HfZrO, HfAlO_(x), ZrO, ZrO₂, ZrSiO₂, AlO, AlSiO, Al₂O₃, TiO,TiO₂, LaO, LaSiO, Ta₂O₃, Ta₂O₅, Y₂O₃, SrTiO₃, BaZrO, BaTiO₃ (BTO),(Ba,Sr)TiO₃ (BST), Si₃N₄, hafnium dioxide-alumina (HfO₂—Al₂O₃) alloy,other suitable high-k dielectric material for metal gate stacks, orcombinations thereof. The high-k dielectric layer is formed by any ofthe processes described herein, such as ALD, CVD, PVD, oxidation-baseddeposition process, other suitable process, or combinations thereof.Gate electrode layer(s) of the gate structure are formed over gatedielectric; gate electrodes includes a conductive material, such aspolysilicon, aluminum, copper, titanium, tantalum, tungsten, molybdenum,cobalt, TaN, NiSi, CoSi, TiN, WN, TiAl, TiAlN, TaCN, TaC, TaSiN, otherconductive material, or combinations thereof. In some embodiments, agate electrode includes a work function layer and a bulk conductivelayer. The work function layer is a conductive layer tuned to have adesired work function (e.g., an n-type work function or a p-type workfunction), and the conductive bulk layer is a conductive layer formedover the work function layer. In some embodiments, the work functionlayer includes n-type work function materials, such as Ti, silver,manganese, zirconium, TaAl, TaAlC, TiAlN, TaC, TaCN, TaSiN, othersuitable n-type work function materials, or combinations thereof. Insome embodiments, the work function layer includes a p-type workfunction material, such as ruthenium, Mo, Al, TiN, TaN, WN, ZrSi₂,MoSi₂, TaSi₂, NiSi₂, WN, other suitable p-type work function materials,or combinations thereof. The bulk (or fill) conductive layer includes asuitable conductive material, such as Al, W, Ti, Ta, polysilicon, Cu,metal alloys, other suitable materials, or combinations thereof. A gateelectrode is formed by any of the processes described herein, such asALD, CVD, PVD, plating, other suitable process, or combinations thereof.

The source/drain features 207 include doped regions—e.g., n-type dopantsand/or p-type dopants—suitable for providing features of thesemiconductor device. In some embodiments, the source/drain features 207comprise epitaxial material. An epitaxy process can use CVD depositiontechniques (for example, LPCVD, VPE, and/or UHV-CVD), molecular beamepitaxy, other suitable epitaxial growth processes, or combinationsthereof. In some embodiments, for the n-type transistors, epitaxialsource/drain features include silicon, which can be doped with carbon,phosphorous, arsenic, other n-type dopant, or combinations thereof (forexample, forming Si:C epitaxial source/drain features, Si:P epitaxialsource/drain features, or Si:C:P epitaxial source/drain features). Insome embodiments, for the p-type transistors, epitaxial source/drainfeatures include silicon germanium or germanium, which can be doped withboron, other p-type dopant, or combinations thereof (for example,forming Si:Ge:B epitaxial source/drain features).

In some implementations, the isolation features 209 are shallow trenchisolation (STI) structures, deep trench isolation (DTI) structures,local oxidation of silicon (LOCOS) structures, other suitable isolationstructures, or combinations thereof. The isolation features 209 mayinclude a multi-layer structure of suitable dielectrics such as oxides.

The dielectric layer 211 may be an interlayer dielectric (ILD) part ofan MLI. The dielectric layer 211 may include a dielectric materialincluding, for example, silicon oxide, carbon doped silicon oxide,silicon nitride, silicon oxynitride, TEOS-formed oxide, PSG, BSG, BPSG,FSG, xerogel, aerogel, amorphous fluorinated carbon, parylene, BCB-baseddielectric material, polyimide, other suitable dielectric material, orcombinations thereof. In some embodiments, dielectric layer 211 includesa dielectric material having a dielectric constant that is less than adielectric constant of silicon dioxide (e.g., k<3.9). In someembodiments, dielectric layer 211 includes a dielectric material havinga dielectric constant that is less than about 2.5 (i.e., an extremelow-k (ELK) dielectric material), such as silicon dioxide (SiO2) (forexample, porous silicon dioxide), silicon carbide (SiC), and/orcarbon-doped oxide (for example, a SiCOH-based material (having, forexample, Si—CH3 bonds)), each of which is tuned/configured to exhibit adielectric constant less than about 2.5. The dielectric layer 211 caninclude a multilayer structure having multiple dielectric materials.

As introduced above, the MLI 213 includes insulating layers andconductive layers. MLI 213 electrically couples various devices (forexample, p-type transistors and/or n-type transistors, resistors,capacitors, and/or inductors) and/or components (for example, gateelectrodes and/or epitaxial source/drain features of p-type transistorsand/or n-type transistors) disposed on the semiconductor structure 202,such that the various devices and/or components can operate as specifiedby design requirements of semiconductor device. MLI 213 includes acombination of dielectric layers and electrically conductive layers(e.g., metal layers) configured to form various interconnect structures.The conductive layers are configured to form vertical interconnectfeatures, such as device-level contacts and/or vias, and/or horizontalinterconnect features, such as conductive lines. Vertical interconnectfeatures typically connect horizontal interconnect features in differentlayers (or different planes) of MLI 213. During operation, theinterconnect features are configured to route signals between thedevices and/or the components of devices and/or distribute signals (forexample, clock signals, voltage signals, and/or ground signals) to thedevices and/or the components of devices.

In some embodiments, other features are present on the semiconductorstructure 202 including other portions of active or passive devices andinterconnections thereof. In other embodiments, various ones or all ofthe features or devices discussed above are omitted. For example, in anembodiment, the semiconductor structure 202 includes a substrate 201such as a silicon substrate and the substrate itself is the target layerto be patterned.

In some implementations, block 102 includes forming a target layer ortarget layers over the semiconductor structure. In an embodiment, thetarget layer is an interlayer dielectric (ILD) of a multi-layerinterconnect (MLI) such as the ILD layer discussed above. The targetlayer may be an ILD layer of a higher MLI layer, such as ILD-1, ILD-3and the like, the numerical designation providing the number of layersabove the semiconductor devices. Semiconductor devices can have anynumber of metallization/ILD layers, in many implementations over 5 or 10layers. Other examples of target layers may also be possible including asemiconductor substrate, other dielectric layers, semiconductor layers,conductive layers, and/or other suitable layers implemented insemiconductor fabrication.

Referring to the example of FIG. 3 , a target layer 302 is provided on asemiconductor structure 202. In an embodiment, the target layer 302 isan interlayer dielectric (ILD) part of an MLI. A deposition process(such as CVD, PVD, ALD, HDPCVD, MOCVD, RPCVD, PECVD, LPCVD, ALCVD,APCVD, FCVD, HARP, HDP, other suitable methods, or combinations thereof)may be used to provide the target layer.

In an embodiment, the target layer 302 is an ILD layer including adielectric material including, for example, silicon oxide, carbon dopedsilicon oxide, silicon nitride, silicon oxynitride, TEOS-formed oxide,PSG, BSG, BPSG, FSG, xerogel, aerogel, amorphous fluorinated carbon,parylene, BCB-based dielectric material, polyimide, other suitabledielectric material, or combinations thereof. In some embodiments, ILDlayer includes a dielectric material having a low-k dielectric or an ELKdielectric. The target layer 302 can include a multilayer structurehaving multiple dielectric materials.

In other implementations, the target layer 302 may be another dielectriclayer, a conductive layer (e.g., interconnection, plate of capacitor,electrode of memory cell, etc.), and/or a semiconductor layer (e.g.,gate feature, fin structure, epitaxial layer, etc.) In animplementation, the target layer 302 is a portion of a semiconductorsubstrate, such as substrate 201. In such a case, the additionalelements of the semiconductor structure 202 are not included and thetarget layer is part of the substrate 201 and/or directly disposed onthe substrate 201.

The method 100 then proceeds to block 104 where a masking layer(s) isformed over the target layer. The masking layer may include a hard maskmaterial. In some embodiments, the masking layer may be a sacrificiallayer used for patterning and/or protection of underlying layers. Insome embodiments, the masking layer may be a multi-layer structure. In afurther embodiment, the masking layer is a tri-layer structure includinga hard mask layer (e.g., metal-containing, organic) between dielectricmaterial layers. The masking layer may include anti-reflective coatinglayer(s).

Referring to the example of FIG. 3 , a masking layer 304 is formed overthe target layer 302. In an embodiment, the masking layer 304 includes afirst layer 304A, a second layer 304B, and a third layer 304C. In someimplementations, the first layer 304A and the third layer 304C includesilicon oxide or another dielectric material. In some implementations,the second layer 304B includes a hard mask material such as a metal hardmask material. In an embodiment, the metal hard mask material is TiN.Other exemplary metal hard mask materials include Ti, Ta, W, TaN, WN,and/or other suitable compositions. In other embodiments, the secondlayer 304B is an organic hard mask. In other embodiments, the hard masklayer is differently configured based upon the lithography needs.

In some implementations, the thickness of the first layer 304A and/orthe third layer 304C are between approximately 100 Å and 500 Å. In afurther embodiment, the thickness of the first layer 304A and/or thethird layer 304C are between approximately 200 Å and 300 Å. In someimplementations, the thickness of the second layer 304B is betweenapproximately 100 Å and 500 Å. In a further embodiment, the thickness ofthe second layer 304B is between approximately 200 Å and 300 Å. Theselected thickness depends upon the etch film selectivity and the etchprocess parameters. For example, the closer the etch selectivity betweenmaterials, an increased thickness may be beneficial. In an embodiment,the masking layer of block 104 is omitted.

The method 100 then proceeds to block 106 where a first layer of amulti-layer patterning stack is deposited. In some implementations, themulti-layer patterning stack may include three-layers as discussedbelow. For example, the three layers may include a top or image layer, amiddle or transfer layer, and a bottom or base layer. These layers arediscussed in the order of deposition, i.e., from bottom to top withrespect to blocks 106, 108 and 110 of the method 100. In someembodiments, the multi-layer patterning stack provides anorganic/inorganic/organic stack of layers.

In an embodiment, block 106 deposits the first layer (e.g., base orbottom layer) of a multi-layer patterning stack. The first layer maycomprise organic material. In an embodiment, the first layer is a BARClayer. The BARC material may be an organic material selected for thephotolithography process to be performed in block 112. In an embodiment,the BARC material is an anti-reflective coating suitable for radiationat 13.5 nm (EUV), now known or later developed. In an embodiment, theBARC is a formed by spin-on coating. In an embodiment, the first layeris a spin-on organic hard mask (SOHM).

In other embodiments, the first layer may comprise a carbon-basedmaterial having a carbon (C) composition greater than fifty (50) atomicpercent % In addition to the carbon, other components of thecarbon-containing layer include hydrogen (e.g., amorphous hydrogenatedcarbon). In an embodiment, the carbon-based layer is amorphous carbon(a-Carbon). In some embodiments, no other atomic components arepurposefully deposited in forming the carbon-containing layer, e.g.,other than carbon and hydrogen. For example, the atomic percent ofcarbon may be between approximately 50 and 75% and the remaining 50 to25 atomic % may be hydrogen. In a further embodiment, the atomic percentof carbon is approximately 65 atomic % and the atomic percent ofhydrogen is approximately 35 atomic %. In some implementations, thefirst layer of carbon-containing material is deposited by chemical vapordeposition (CVD) process such as plasma-enhanced CVD (PECVD). Other CVDprocesses include high density plasma CVD (HDPCVD), metal organic CVD(MOCVD), remote plasma CVD (RPCVD), plasma enhanced CVD (PECVD),low-pressure CVD (LPCVD), atomic layer CVD (ALCVD), atmospheric pressureCVD (APCVD), sub-atmospheric vapor deposition (SAVCD), or other suitablemethods. In an embodiment, the first layer of carbon-containing materialis deposited by physical vapor deposition (PVD) such as plasma enhanced(PE) PVD. Other PVD processes include sputtering, electron beam, thermalevaporation, or other suitable methods. In an embodiment, the firstlayer of carbon-containing material is deposited by atomic layerdeposition (ALD) such as plasma-enhanced (PE) ALD.

In some implementations, the first layer is provided as a BARC layer andis formed to a thickness of between 500 Angstroms and 1000 Angstroms(Å). In a further embodiment, the first layer is a deposited (e.g., PVD,CVD, ALD) carbon-containing layer and has a thickness of betweenapproximately 50 and 500 Å. In a further embodiment, the thickness isbetween approximately 200 and 300 Å. The thickness of thecarbon-containing layer may be selected based on the etch selectivity tosurrounding layers, the tuning of the etching process, the underlyingtopography, and/or other criteria. For example, a topography underlyingthe carbon-containing first layer having a high-aspect ratio may demandan increased thickness to suitably cover the topography. In anembodiment, an underlying topography necessitates depositing the firstlayer by spin-on coating to provide suitable coverage for the topography(e.g., gap fill). In an embodiment, the etch selectivity between thecarbon-containing layer and the underlying layer (e.g., masking layer,target layer, intervening layer) may impact the thickness, for example,a greater thickness may be required for a decreased selectivity betweenthe carbon-containing layer and the target layer.

In some embodiments, prior to forming the first layer, another layer isformed between the hard mask and the first layer. In certainimplementations, this layer is a mandrel layer, such as a layer used toform mandrels in a double patterning process. In other embodiments, thecarbon-containing layer is deposited directly on the masking layer(e.g., 304C), such as in the single patterning process.

Referring to the example of FIG. 4 , a bottom layer 402 is formed overthe semiconductor structure 202. In an embodiment, the bottom layer 402is a BARC provided by spin-on coating. In an embodiment, the bottomlayer 402 may be a carbon-containing layer (e.g., amorphous carbon) asdiscussed above that may be deposited by one of PVD, ALD, or CVDprocesses.

The method 100 then proceeds to block 108 where a second layer of amulti-layer patterning stack is deposited. The second layer of amulti-layer patterning stack may be a silicon-containing layer.

In some embodiments, the second layer may comprise a silicon-basedmaterial having a silicon (Si) composition greater than fifty (50)atomic percent %. In an embodiment, the silicon-containing second layeris amorphous silicon. In a-Si, the atoms form a continuous randomnetwork with numerous unconnected dangling bonds. Other components ofthe silicon-containing layer include hydrogen, thus providinghydrogenated amorphous silicon (e.g., a-Si:H) for example, attaching thedangling bond sites. In some embodiments, the second layer as depositedconsists of silicon and hydrogen and other atoms are not provided. Inthe present disclosure, a reference to amorphous silicon (a-Si) isinclusive of a-Si:H. In some implementations, the percentage of Hpresent in the a-Si is dependent on the desired properties of the layer,for example, increasing H may increase the hardness. Exemplarycompositions for the a-Si layer include between over 50 atomic % Si to75 atomic % Si and less than 50 atomic % H to 25 atomic % H.

In some implementations, the second layer of silicon-containing material(e.g., a-Si) is deposited by chemical vapor deposition (CVD) processsuch as plasma-enhanced CVD (PECVD). Other CVD processes include highdensity plasma CVD (HDPCVD), metal organic CVD (MOCVD), remote plasmaCVD (RPCVD), plasma enhanced CVD (PECVD), low-pressure CVD (LPCVD),atomic layer CVD (ALCVD), atmospheric pressure CVD (APCVD),sub-atmospheric vapor deposition (SAVCD), other suitable methods. In anembodiment, the second layer of silicon-containing material is depositedby physical vapor deposition (PVD) such as plasma enhanced (PE) PVD.Other PVD processes include sputtering, electron beam, thermalevaporation. In an embodiment, the second layer of silicon-containingmaterial is deposited by atomic layer deposition (ALD) such asplasma-enhanced (PE) ALD. The deposition of the silicon-containing layer(e.g., PVD, ALD, CVD processes) can be characterized as usingprocess(es) where molecules of chemical compounds serving as precursorsare delivered to the substrate surface and chemically modified to obtainthe desired film. These depositions processes are in contrast tospin-coating or dip-coating processes.

In some implementations, the deposition of the silicon-containing layerby the methods discussed above includes providing a precursor reactivegas and an inert gas. Example precursors include silicon-containingcompounds. In an embodiment, the precursor includes a silicon sourcesuch one of silane (SiH4) or disilane (Si2H6). Example inert gasesinclude nitrogen, argon, helium, xenon, other suitable carrier gasconstituent, or combinations thereof. In an embodiment, the inert gasincludes at least one of argon (Ar) or helium (He). Thesilicon-containing layer may be deposited by introduction of gasesprecursors (with inert gases) to a chamber, where a heated semiconductorstructure is disposed. Reactions between the precursors (and/or surfaceof the semiconductor structure) creates a solid film layer ofsilicon-containing material on the semiconductor structure. This processmay be performed by the tool illustrated in FIG. 30 , discussed below.

The deposition process of the silicon-containing first layer of amulti-layer patterning stack may include a process temperature ofbetween room temperature (RT) to 600 degrees Celsius. The depositionprocess of the silicon-containing first layer of a multi-layerpatterning stack may include a process pressure of between approximatelyzero (0) and 100 torr. In an embodiment, the temperature and/or pressureare determined to provide suitable dissociation of the precursors and/orexcitability of the silicon atoms. In an embodiment, the processtemperature is a temperature of the wafer and/or the process chamber.The power of the deposition may be between approximately 10 and 25 MHz.The power is selected to provide suitable disassociation and reaction ofthe precursors. The greater the power the higher the disassociation butmay risk arcing or other issues in tool performance.

In some implementations, the silicon-containing second layer isdeposited to a thickness of 50 to 500 Angstroms (Å). In a furtherembodiment, the thickness of the silicon-containing film is betweenapproximately 100 and 200 Å. The thickness of the silicon-containinglayer may be selected based on the etch selectivity to surroundinglayers and the tuning of the etching process to provide suitable patterntransfer performance.

In some embodiments, the silicon-containing layer is deposited directlyon the first layer. Thus, in some implementations, a spin-on organiccoating (e.g., BARC) is directly interfacing an amorphous silicon layerto provide the base layer and the middle layer of a tri-layer stack. Inan embodiment, a carbon-containing layer (e.g., greater than 50% atomiccarbon, such as a-C) is directly interfacing an amorphous silicon layer.In some implementations, these depositions of block 106 and 108 areperformed in-situ for example, in a tool such as illustrated in FIG. 30below. In some embodiments, block 108 is provided in a tool such asillustrated in FIG. 30 , while block 106 includes spin-on coating thesilicon-containing layer.

In an embodiment, the interface between the silicon-containing layer andthe carbon-containing layer may be a discrete interface transitioningfrom a-C to a-Si. In some embodiments, a structure is formed with acontinuous variation in the C to Si ratio.

In some implementations of the method 100, as discussed above thesilicon-containing layer is deposited as amorphous silicon through, forexample, CVD, PVD, or ALD processes. In some embodiments, the a-Simaterial is subsequently modified in composition. For example, during asubsequent patterning step of the a-Si, an etching process may alterthis composition (a-Si) in whole or in part. For example, whenimplementing an oxygen-comprising etch gas (for example, O2), thesilicon-containing layer may getter oxygen atoms from the etchant gas.Further, when an etching process (e.g., comprising an oxygen-comprisingetch gas) etches the underlying carbon-containing layer, thesilicon-containing layer may getter oxygen and/or carbon that convertssome or all of the deposited a-Si material to an SiO₂ polymercomposition. In some implementations, this conversion (e.g., addition ofoxygen or carbon) occurs at a portion of the silicon-containing layersurfaces exposed during the etching process.

Referring to the example of FIG. 5 , a middle layer 502 is formed overthe semiconductor structure 202. In an embodiment, the middle layer 502is a silicon-containing layer as discussed above including over 50atomic % of Si and being deposited by at least one of PVD, ALD, or CVD.For example, in some embodiments, the middle layer 502 is amorphoussilicon.

The method 100 then proceeds to block 110 where a photosensitive layerof the multi-layer patterning stack is deposited. The photosensitivelayer may also be referred to as a photoresist or simply resist. Theresist layer may be deposited by spin coating process. For example, thespin-coating may include applying a liquid polymeric material onto thesemiconductor structure 202 (e.g., the middle layer 502). In anembodiment, the resist layer is a radiation sensitive material to thedesired wavelength, such as a photoresist including an I-line resist, aDUV resist including a krypton fluoride (KrF) resist and argon fluoride(ArF) resist, a EUV resist, an electron beam (e-beam) resist, and an ionbeam resist. In a further embodiment, the resist is a 193-nm resist. Ina further embodiment, the resist is an EUV resist sensitive to the 13.5nm wavelength exposure of an EUV lithography process. In an embodiment,the resist is sensitive to EUV radiation and is further fornegative-tone development (NTD), i.e., its solubility in a NTD developerdecreases upon EUV radiation.

The resist layer may include a polymer back-bone and one or morephotosensitive components targeted to the radiation wavelength to beused to pattern the resist layer. The wavelengths include thoseassociated with lithography processes such as deep ultraviolet (DUV)lithography, extreme ultraviolet (EUV) lithography, electron beam(e-beam) lithography, x-ray lithography, and/or other lithographyprocesses. In an embodiment, the resist that employs the chemicalamplification is generally referred to as a “chemically amplified resist(CAR).” The photoresist includes a polymer that resists to etching orion implantation; an acid generating compound (e.g., photo acidgenerator (PAG)); and a solvent. In some examples, the polymer alsoincludes at least one acid labile group (ALG) that responds to acid. Insome embodiments, the resist includes polymeric chemically amplified forexample by polyhydroxystyrene (PHS) group providing sensitivity to EUVlithography for example. In some implementations, non-chemicallyamplified resist is provided such as polymethylmethacrylate (PMMA)resists. While many resist options are organic, inorganic resists arealso possible.

In some embodiments, the resist layer is formed directly on the middleor second layer (e.g., a-Si). In some embodiments, a small amount ofsilicon oxide (e.g., native SiO2) is formed on the top of the a-Si layerand the resist layer is formed thereon. In other embodiments, such asdiscussed below, an adhesion layer interposes the resist layer and themiddle layer.

Referring to the example of FIG. 6 , a resist layer 602 is deposited.The resist layer 602, the middle layer 502 and the bottom layer 402provide the multi-layer patterning stack 604, in particular, a tri-layerstack.

The method 100 then proceeds to block 112 where the photosensitive layeris patterned using a lithography technique. After deposition of theresist layer, which may be conformal, in some implementations thephotolithography process includes performing a pre-exposure bakingprocess, performing an exposure process using a mask, performing apost-exposure baking process, and performing a developing process.During the exposure process, the resist layer is exposed to radiationenergy (such as ultraviolet (UV) light, deep UV (DUV) light, or extremeUV (EUV) light), where the mask blocks, transmits, and/or reflectsradiation to the resist layer depending on a mask pattern of the maskand/or mask type (for example, binary mask, phase shift mask, or EUVmask), such that an image is projected onto the resist layer thatcorresponds with the mask pattern. In some implementations, the methodincludes using immersion lithography. Since the resist layer issensitive to radiation energy as discussed above, exposed portions ofthe resist layer chemically change, and exposed (or non-exposed)portions of the resist layer are dissolved during the developing processdepending on characteristics of the resist layer and characteristics ofa developing solution used in the developing process. That is, inlithography patterning, after a resist film is exposed to a radiation,such as a EUV radiation (or alternatively other radiation, such as anelectron beam), it is developed in a developer (a chemical solution).The developer removes portions (such as exposed portions as in apositive-tone photoresist or unexposed portions as in a negative-tonephotoresist) of the resist film, thereby forming a resist pattern whichmay include line patterns and/or trench patterns. After development, thepatterned resist layer includes a resist pattern that corresponds withthe mask. It is noted that in some implementations, the first layer andthe silicon-containing layer are not affected (e.g., no chemical change)from the exposure or development. In an embodiment, the a-Si compositionof the second layer interfaces the patterned resist.

Referring to the example of FIG. 7 , the resist layer 602 is patternedto form a series of masking element features 602′ comprised of exposedand developed resist, and interposing openings. In an embodiment, thepattern is provided by an EUV lithography technique as discussed above.

The method 100 then proceeds to block 114 where the pattern of thephotosensitive layer is etched into the remaining layers of themulti-layer patterning stack to form a masking element. FIGS. 8, 9, 10,and 11 exemplify the etching process(es) used to create the maskingelement by etching the pattern of the resist layer 602′ into theunderlying middle layer 502 and bottom layer 402 of the tri-layerpatterning stack 604. The etching process(es) may include a reactive ionetch or plasma etching system. The etching process may implement ahydrogen-comprising etch gas (e.g., H2 and/or CH4), anitrogen-comprising etch gas (for example, N2 and/or NH3), achlorine-comprising etch gas (for example, Cl2, CHCl3, CCl4, and/orBCl3), an oxygen-comprising etch gas (for example, O2), afluorine-comprising etch gas (for example, F2, CH3F, CH2F2, CHF3, CF4,C2F6, SF6, and/or NF3), a bromine-comprising etch gas (e.g., Br, HBr,CH3Br, CH2Br2, and/or CHBr3), an iodine-comprising etch gas, othersuitable etch gas, or combinations thereof. In some embodiments, the dryetching process can use a carrier gas to deliver the etch gas. Thecarrier gas includes nitrogen, argon, helium, xenon, other suitablecarrier gas constituent, or combinations thereof.

In some implementations, a first step of block 114 is a “descumprocess.” The descum process may remove (residual) portions of theresist from areas where they are not intended to be, for example if thefidelity to the intended pattern is not complete. This process removesthe undesired residual resist material, while also decreasing thedesired patterned resist in height. In some embodiments, the descumprocess may slightly etch the underlying middle layer (a-Si) of themulti-layer patterning stack. FIG. 8 is illustrative of theconfiguration of the multi-layer patterning stack after the descumprocess including slight etching into the middle layer 502. The heightof the resist features 602′ has been decreased and in someimplementations, the top surface rounded. A variety of etchingconditions can be chosen for this descum step such as etching stepsincluding an O2/Ar-based descum, a CF4/CHF3-based descum, and/or othersuitable etchants. As discussed above, in some implementations, thedescum step introduces oxygen (or carbon) atoms that can be gettered bythe a-Si middle layer including at the regions of curvilinear, recessedtop surface of the a-Si middle layer.

Block 114 may proceed to include an etching process of the middle layer,or the silicon-containing layer. In an embodiment, this etching processprovides an etch selective to the silicon-containing layer, such asselective silicon. The etching process patterns the silicon-containingmiddle layer according to the pattern of the resist. Referring to theexample of FIG. 9 , the middle layer 502 is etched providing a patternedmiddle layer 502′. The etching of the middle layer 502 may stop at a topsurface of the bottom layer 402. In some implementations, the patternedmiddle layer 502′ includes tapered sidewalls, for example, due to thedirectional etching and the post-descum profile. The dry (e.g., plasma)etching process may include an oxygen-comprising etch gas (for example,O2), a fluorine-comprising etch gas (for example, F2, CH3F, CH2F2, CHF3,CF4, C2F6, SF6, and/or NF3), a bromine-comprising etch gas (e.g., Br,HBr, CH3Br, CH2Br2, and/or CHBr3), and/or other suitable etchants. Asdiscussed above, in some implementations the etchant introduces atoms(e.g., oxygen) into the surroundings which are gettered by the patternedsecond layer.

The patterned middle layer 502′, e.g., patterned a-silicon layer, mayhave an improved line edge roughness (LER) because of the beneficialproperties achieved for its composition during the deposition step(e.g., density, modulus, hardness) as discussed above.

Block 114 may proceed to include an etching process of the bottom layer.The etching process patterns the organic bottom layer according to thepattern of the resist and/or the patterned middle layer. In someimplementations, the resist layer 602′ is removed during the etchingprocess of the bottom layer 402. For example, if the compositions ofbottom layer 402 and the resist layer 602 are similar (e.g., organiccarbon-based), the etchant may remove both compositions. As discussedabove, in some implementations the etchant introduces atoms from theadjacent layers (e.g., carbon from the first layer) into thesurroundings, which are then gettered by the patterned second layer.

Referring to the example of FIG. 10 , the bottom layer 402 is etchedproviding a patterned bottom layer 402′. The etching of the bottom layer402 may stop at a top surface of the masking layer 304.

A benefit of some embodiments of the method 100 is that after and duringthe etching process to pattern the bottom layer 402, there may be lessloss of the patterned middle layer 502′ due to the composition anddeposition method of the middle layer 502. In some implementations, forexample, when not providing an a-Si deposited layer by ALD, PVD, or CVDas discussed above, the patterned middle layer 502′ (e.g., SOG, SiOC,SiON) may be fully or substantially removed from the device. In anembodiment where a-Si is provided as a silicon-containing layer asdiscussed above, at least at height h1 of the patterned middle layer502′ may remain. In some embodiments, the height h1 is at least 5 nm. Insome embodiments, a height h1 of approximately 5-15 nm remain. In anembodiment, a ratio of h1 to h2 is approximately 1:2.5 to 1:5. In anembodiment, a ratio of h1 to d1 is 2:1 to 10:1. This remaining height h2may result from an improved etch selectivity between the second layerand the first layer. In some implementations, the gettering of atoms(e.g., oxygen) discussed above furthers this etch selectivity.

In some implementations of the method 100 and block 114, the resultantpatterned silicon-containing layer (and bottom layer) may be trimmed,which refers to a reduction in width of the features. Referring to theexample of FIG. 11 , the patterned features 502′ and 402′ are decreasedin width (x-direction) to provide thinner features (w2). The trimmingmay be performed by suitable etching process such as an isotropic etchto achieve the desired dimension (e.g., critical dimension). In someimplementations, the trimming process may reduce the dimension below thelithography limit of the process implemented in block 112. The trimmingmay decrease the width by, for example, 10-30%. It is noted that the ifthe resultant width w2 is too thin, the aspect ratio of the patternedfeatures may risk collapse.

The method 100 then proceeds to block 116 where the resultant patternedfeatures of the multi-layer patterning stack are used as a maskingelement during the patterning of underlying layers such as maskinglayers. The patterning of the underlying layers is dependent on thepatterning method being implemented by the method 100. In someembodiments, a target layer may be directly patterned using the maskingelement provided by the patterned multi-layer patterning stack and thus,block 116 is omitted from the method 100. In some embodiments, otherpatterning layers such as the underlying masking layer(s) (e.g., metalhard mask) may be directly patterned using the masking element providedby the patterned multi-layer patterning stack, which in turn are used topattern underlying layers. The etching process(es) may include areactive ion etch or plasma etching system. The dry etching process mayimplement a hydrogen-comprising etch gas (e.g., H2 and/or CH4), anitrogen-comprising etch gas (for example, N2 and/or NH3), achlorine-comprising etch gas (for example, Cl2, CHCl3, CCl4, and/orBCl3), an oxygen-comprising etch gas (for example, O2), afluorine-comprising etch gas (for example, F2, CH3F, CH2F2, CHF3, CF4,C2F6, SF6, and/or NF3), a bromine-comprising etch gas (e.g., Br, HBr,CH3Br, CH2Br2, and/or CHBr3), an iodine-comprising etch gas, othersuitable etch gas, or combinations thereof. In some embodiments, the dryetching process can use a carrier gas to deliver the etch gas. Thecarrier gas includes nitrogen, argon, helium, xenon, other suitablecarrier gas constituent, or combinations thereof. The wet etchingprocess may implement a wet etchant solution that includes H₂SO₄(sulfuric acid), H₂O₂ (hydrogen peroxide), NH₄OH (ammonium hydroxide),HCl (hydrochloric acid), HF (hydrofluoric acid), DHF (diluted HF), HNO₃(nitric acid), H₃PO₄ (phosphoric acid), H₂O (water) (which can bedeionized water (DIW) or ozonated de-ionized water (DIWO₃)), ozone (O₃),other suitable chemicals, or combinations thereof.

Referring to the example of FIG. 12 , the patterned bottom layer 402′ isused as a masking element while etching the masking layer 304 and inparticular the dielectric layer 304C to form patterned layer 304C′. Inan embodiment, the etching process is selective to the composition ofthe dielectric layer 304C, such as selective to silicon oxide. In someembodiments, the silicon-containing layer 502′ is removed during theetching of the dielectric layer 304C. In some embodiments, the etchingprocess stops at the hard mask layer 304B, for example, a metal hardmask composition. The etching process may provide for a rounded topsurface of the patterned carbon-containing layer 402′.

Referring to the example of FIG. 13 , the patterned bottom layer 402′(and the patterned dielectric layer 304C′) may be used as an etchingmask during the etching of the masking layer 304 and in particular themetal hard mask layer 304B to form the patterned hard mask layer 304B′.In some implementations, etching the metal hard mask layer 304B includesan over-etch that extends into the underlying dielectric layer 304A(e.g., silicon oxide). Generally, the etchant however may be selectiveto the hard mask layer 304B′ material.

After the etching of the metal hard mask layer 304B, a flush or cleanprocess may be performed. In some implementations, the flush process mayremove the patterned bottom layer 402′ as illustrated in FIG. 14 . Thepatterned hard mask layer 304B′ generally is suitable to provide amasking element for patterning underlying target layer(s).

The method 100 then proceeds to block 118 where the masking elementdeveloped by the previous blocks is used during the etching of a targetlayer(s). Referring to the example of FIG. 15 , the target layer 302 ispatterned by an etching process, while the patterned metal hard masklayer 304B′ is used as a masking element defining the pattern to beformed. The patterned target layer 302′ is provided with the samepattern as defined in the overlying resist layer 602 (in someembodiments, having been further defined by a trim process). It is notedin this respect, the method 100 has been described as providing a singlepatterning process (1 photolithography process); however, otherembodiments that apply the method 100 including those withmultiple-photo and etch processes are possible. For example, doublepatterning lithography (DPL) process (for example, alithography-etch-lithography-etch (LELE) process, a self-aligned doublepatterning (SADP) process, a spacer-is-dielectric (SID) SADP process,other double patterning process, or combinations thereof), a triplepatterning process (for example, alithography-etch-lithography-etch-lithography-etch (LELELE) process, aself-aligned triple patterning (SATP) process, other triple patterningprocess, or combinations thereof), other multiple patterning process(for example, self-aligned quadruple patterning (SAQP) process), orcombinations thereof.

In some embodiments, the underlying layer 304A is a similar compositionto that of the target layer 302 and thus also patterned during theetching process to form patterned layer 304A′. In other embodiments, thelayer 304A is patterned separately to form patterned layer 304A′. In anembodiment, any remaining portion of the hard mask layer 304 may bestripped off after patterning the target layer 302.

In some embodiments, the target layer 302 is an ILD layer and thepatterned target layer 302′ may define openings or trenches within whichmetallization of the MLI will be formed. In such an embodiment, themethod 100 proceeds to filling the trenches with a conductive material,such as a metal; and polishing the conductive material using a processsuch as chemical mechanical planarization (CMP) to expose the patternedILD layer, thereby forming the metal lines in the ILD layer. This isillustrated in the conductive features 1602 of FIG. 16 , which mayprovide metal interconnect line.

In some embodiments, the target layer 302 is a conductive layer to beused for metal lines and is made of copper, aluminum, the like, or acombination thereof. In other embodiments, the target layer 302 is adielectric layer, such as a low-k dielectric layer, a polymer layer, orthe like. In another embodiment, the target layer is a material suitablefor a gate structure forming a gate (or dummy gate structure) of adevice, for example, polysilicon. In yet other embodiments, the targetlayer 302 is a substrate and is made of a semiconductor material such assilicon, germanium, or other suitable materials. In such an embodiment,the trenches formed in the target layer of the substrate may defineisolation features between fin-like structures suitable for fabricatingfin-type field effect transistors (FinFET). In an embodiment, the targetlayer 302 is a mandrel layer. The mandrel layer may be a maskingmaterial such as silicon nitride, an oxide, silicon, amorphous silicon,a combination thereof or any other material that may be patterned andselectively removed. The patterned mandrel layer is then used forfurther patterning processes for example to achieve smaller dimensionsas part of a multi-patterning process such as applying the method 100 toa double patterning technique. The above are non-limiting examples ofdevices/structures that can be made and/or improved using the method 100according to various aspects of the present disclosure.

In some embodiments, due to the properties of the patterning materialsand/or steps discussed above, the patterned target layer has very smoothedges and sidewalls, therefore low line-edge roughness (LER) andline-width roughness (LWR) and/or improved local critical dimensionuniformity (LCDU). In some embodiments, this is because the material anddeposition process (e.g., ALD, CVD, PVD) forming the silicon-containingfilm, provide for a material layer that possess high density, improvedhardness, desirable modulus, high etch selectivity and/or otherbenefits. In some implementations, the beneficial properties, such ashigh density, result because impurities and/or undesired bonding withinthe material layer can be dissociated by introduction of plasma in thedeposition process. The film properties including density, modulus,hardness, etc may be modified through deposition processes knobs such asthe gas flow (precursor, inert gases), power, process temperature,substrate temperature, and the like.

In an embodiment of the method 100, an additional block is provided inwhich an adhesion layer is formed in the multi-layer patterning stack.For example, in an embodiment, an adhesion layer may be formed betweenthe middle layer (e.g., silicon-containing layer) and the overlyingresist layer. The adhesion layer may include a material such ashexamethyldisilazane (HDMS) or a bottom antireflective coating (BARC).In some embodiments, the material of BARC is selected based on thelithography process to be formed such as to provide suitableanti-reflective properties depending on the wavelength of radiation. Thethickness of the adhesion layer may be between approximately 0 and 100Angstroms (Å). In the implementation of the adhesion layer being asurfactant, the thickness may be considered 0 Å due to its nature as asurface treatment. FIG. 17 is illustrative of an adhesion layer 1702interposing the patterned resist 602′ and the middle layer 502, asilicon-containing layer. FIG. 17 is substantially similar to FIG. 7 andthe method 100 progresses with the adhesion layer substantially similaras above. The adhesion layer may be patterned with the middle layer 502.

In an implementation of the method 100, a topographically varyingstructure, such as a patterned layer, may be disposed under themulti-layer patterning stack. Referring to the example of FIG. 18 , themulti-layer patterning stack including resist layer 602, the middlelayer 502 and the bottom layer 402 is disposed over a plurality offeatures 1802 that are disposed on the masking layer 306.

As illustrated in FIG. 18 , the bottom layer 402 directly interfaces theplurality of features 1802 and fills the gap therebetween. In someembodiments, the bottom layer 402 is thicker than the plurality offeatures 1802 by 1.2-4 times the height of the plurality of features1802. In an embodiment, the bottom layer 402 is deposited by spin-oncoating to provide suitable gap filling between the plurality offeatures 1802. After deposition, the bottom layer 402 may be planarizedby a suitable process such as chemical mechanical polish (CMP) prior toformation of the second layer 502.

In an embodiment, the plurality of features 1802 are sacrificialmandrels (e.g., silicon or other sacrificial material) to be used in amulti-patterning scheme such as in a double patterning technique. Forexample, the method 100 may be employed using a layer of target materialthat is designed to form the plurality of features 1802. A firstmulti-layer patterning stack is provided over the target material topattern the plurality of features 1802. The method 100 may repeat,forming a second multi-layer patterning stack over the plurality offeatures 1802. The second multi-layer patterning stack may further alterthe plurality of features 1802 and/or a pattern of features formed fromsaid plurality of features (e.g., spacer elements formed on thesidewalls of the plurality of features 1802).

Referring now to FIGS. 19 through 29B, illustrated is an embodiment ofthe method 100 implemented in a multi-patterning scheme includingmultiple photolithography and etch processes to pattern a target layer.FIGS. 19 through 29B provide an example of patterning of a back-end-ofthe line (BEOL) features. In particular, a metallization layer of amulti-layer interconnect is patterned. The description of the method 100above applies in full force to the description of the embodimentillustrated by FIGS. 19 through 29B.

FIG. 19 illustrates a device 1900 having a semiconductor structure 202with a plurality of layers formed thereon. In an embodiment, thesemiconductor structure 202 is substantially similar as discussed above,including for example, the presence of active devices such astransistors. Over the semiconductor structure 202 is formed a first ILDlayer 1902 and a first metallization layer 1904 of an MLI thatinterconnects the active devices on the semiconductor structure 202. TheILD layer may include a dielectric material including, for example,silicon oxide, carbon doped silicon oxide, silicon nitride, siliconoxynitride, TEOS-formed oxide, PSG, BSG, BPSG, FSG, xerogel, aerogel,amorphous fluorinated carbon, parylene, BCB-based dielectric material,polyimide, other suitable dielectric material, or combinations thereof.In some embodiments, ILD layer 1902 includes a dielectric materialhaving a dielectric constant that is less than a dielectric constant ofsilicon dioxide (e.g., k<3.9). In some embodiments, ILD layer 1902includes a dielectric material having a dielectric constant that is lessthan about 2.5 (i.e., an extreme low-k (ELK) dielectric material), suchas silicon dioxide (SiO₂) (for example, porous silicon dioxide), siliconcarbide (SiC), and/or carbon-doped oxide (for example, a SiCOH-basedmaterial (having, for example, Si—CH3 bonds)), each of which istuned/configured to exhibit a dielectric constant less than about 2.5.The dielectric layer 1902 can include a multilayer structure havingmultiple dielectric materials. The first metallization layer 1904 may bea conductive material such as copper, aluminum, tungsten, and/or othersuitable materials. The first metallization layer 1904 may be amulti-layer structure including for example, liner layers, barrierlayers, adhesion layers, and/or other suitable layers.

An etch stop layer 1906 is disposed over the ILD layer 1902 and thefirst metallization layer 1904. In an embodiment, the etch stop layer1906 includes multiple layers. The etch stop 1906 may include SiC, SiN,TEOS, hard black diamond (HBD), or other suitable composition. Over theetch stop layer 1906, another ILD layer 1908 is disposed. The ILD layer1908 may be the target layer for patterning. For example, in someimplementations, trenches are to be patterned in the ILD layer 1908within which conductive material (e.g., copper) will be deposited toform a metallization layer by a damascene or dual-damascene process. Insome embodiments, if the first metallization layer 1904 is metallizationlayer “M”, the ILD layer 1908 and the metallization layer that is to beformed within said layer is metallization layer “M+1.” The ILD layer1908 may be substantially similar to the first ILD layer 1902 and mayinclude the same or different composition than that of the first ILDlayer 1902.

Above the target ILD layer 1908, a hard mask layer 1910 is disposed. Insome implementations, the hard mask layer 1910 is substantially similarto the masking layer 304. In an embodiment, the hard mask layer 1910includes a first layer 1910A, a second layer 1910B, and a third layer1910C. In an embodiment, the third layer 1910C is a dielectric layersuch as TEOS. In an embodiment, the second layer 1910B is a metal hardmask layer such as TiN. Other exemplary metal hard mask materialsinclude Ti, Ta, W, TaN, WN, and/or other suitable compositions. In anembodiment, the first layer 1810A is a nitrogen free anti-reflectionlayer (NFARL).

A mandrel layer 1912 is disposed over the hard mask layer 1910. In anembodiment, the mandrel layer 1912 is silicon such as amorphous silicon,polysilicon, or other suitable composition. The mandrel layer 1912, whenpatterned, is used provide sacrificial features implemented to reducethe pitch of the patterned features by providing spacer material overthe features/mandrels, providing spacer features on the sidewalls of themandrels, and subsequently removing the mandrels to allow the spacerfeatures to define a reduced pitch. The mandrel-spacer techniquesinclude self-aligned double patterning (SADP) process which reduces thepitch of the exposed pattern by half, self-aligned quadruple patterning(SAQP) process which reduces the pitch of the exposed pattern by aquarter, and other spacer patterning processes.

Referring now to FIGS. 20A and 20B, a first photolithography process isperformed. The first photolithography process may be referred to as acut process providing in some embodiments to define a space betweensubsequently formed metallization features. FIG. 20A illustrates thatthe first lithography process includes forming a multi-layer patterningstack 604 over the mandrel layer 1912. The multi-layer patterning stack604 includes a bottom layer (carbon-containing layer) 402, a middlelayer (silicon-containing layer) 502, and a resist layer that ispatterned by the first photolithography process to provide patternedresist layer 602″. The multi-layer patterning stack 604 is substantiallysimilar to as discussed above including providing a organic layer 402.In an embodiment, the silicon-containing layer 502 (e.g., a-Si) isdeposited by at least one of CVD, PVD, or ALD processes. In anembodiment, the patterned resist layer 602″ is patterned by an EUVprocess. In other embodiments, other lithography techniques may beimplemented.

FIGS. 21A and 21B illustrate the device 1800 after an etching processproviding the pattern of FIGS. 20A and 20B is performed. The etchingprocess patterns the mandrel layer 1912 to form a patterned mandrellayer 1912′. The multi-layer patterning layer 604 is used as a maskingelement during the etching to form the patterned mandrel layer 1912′.After the etching process, the first multi-layer patterning layer 604may be removed.

Referring now to FIG. 22 , a second photolithography process isperformed. The second photolithography process may define portions of ametallization routing layout including a first set of metallizationlines. FIG. 22 illustrates that the second lithography process includesforming another multi-layer patterning stack 604 over the mandrel layer1912. The multi-layer patterning stack 604 includes a bottom layer(organic layer) 402, a middle layer (silicon-containing layer) 502, anda resist layer that is patterned by the second photolithography processto provide patterned resist layer 602′″. The multi-layer patterningstack 604 is substantially similar to as discussed above includingproviding an organic layer 402 and/or a silicon-containing layer 502deposited by at least one of CVD, ALD, or PVD processes. The multi-layerpatterning stack 604 is formed over a topographically varyingfeature—the patterned mandrel layer 1912′. In an implementation, theorganic layer 402 directly interfaces the patterned mandrel layer 1912′.In an embodiment, the organic layer 402 is deposited by spin-onprocesses to provide suitable gap filling. In an embodiment, the organiclayer 402 is an a-C layer formed by one of CVD, ALD, or PVD. In anembodiment, the patterned resist layer 602′″ is formed by an EUVprocess. In other embodiments, other lithography techniques may beimplemented.

FIGS. 23A and 23B illustrate the device 1800 after an etching processproviding the pattern of FIG. 22 is performed. The etching processfurther patterns the mandrel layer 1912′ to form a patterned mandrellayer 1912″. The multi-layer patterning layer 604 of FIG. 21 is used asa masking element during the etching to form the patterned mandrel layer1912″. After the etching process, the multi-layer patterning layer 604may be removed.

Referring now to FIGS. 24A and 24B, a conformal spacer material layer2402 is formed over the semiconductor structure 202 including themandrels 1912″. The spacer material layer 2402 may include a dielectricmaterial such as, titanium nitride, silicon nitride, silicon oxide,titanium oxide, and/or other suitable materials. The spacer materiallayer 2402 can be formed by various processes, including a depositionprocess by a CVD or PVD process.

Referring now to FIGS. 25A and 25B, the conformal spacer material layer2402 of FIGS. 24A and 24B is etched back to form spacer elements 2502.The etching process may be an anisotropic etching process such as byplasma etching. The width of the spacing “s” may be reduced such that itis below the resolution of the lithography technique applied.

Referring now to FIGS. 26A and 26B, a third photolithography process isperformed. The third photolithography process may define portions of ametallization routing layout including a second set of metallizationlines. FIGS. 26A and 26B illustrate that the third lithography processincludes forming another multi-layer patterning stack 604 over thepatterned mandrel layer 1912″ and the spacer elements 2502. Themulti-layer patterning stack 604 includes a bottom layer (organic layer)402, a middle layer (silicon-containing layer) 502, and a resist layerthat is patterned by the second photolithography process to providepatterned resist layer 602″″. The multi-layer patterning stack 604 issubstantially similar to as discussed above including providing asilicon-containing layer 502 deposited by at least one of CVD, ALD, orPVD processes. The multi-layer patterning stack 604 is formed over atopographically varying feature—the patterned mandrel layer 1912″ andspacer elements 2502. In an implementation, the organic layer 402 isdeposited by spin-on coating to adequately fill the gaps between themandrel layer 1912″. In a further embodiment, a carbon-containing layer402 (a-C) is formed by PVD, CVD, or ALD over each of the patternedmandrel layer 1912″ and the spacer elements 2502. In an embodiment, thepatterned resist layer 602″″ is formed by an EUV process. In otherembodiments, other lithography techniques may be implemented.

FIGS. 27A and 27B illustrate the device 1800 after an etching processproviding the pattern of FIGS. 26A and 26B in combination with thepreviously formed patterned mandrel layer 1912″. Specifically, theresist 602″″ provides openings where certain portions of the patternedmandrel layer 1912″ are removed (e.g., between spacer elements 2502 atthe center of the illustrated portion of device 1800). Afterward, themasking layer 1910 may be etched according to the pattern provided bythe mandrel and spacer elements (i.e., the summation of the first,second and third lithography processes) thereby providing patternedmasking layer 1910′. The patterned masking layer 1910′ includespatterning the hard mask layer 1910B. After patterning to for thepatterned masking layer 1910′, the overlying layers may be removed.

FIGS. 28A and 28B illustrate a subsequent step of providing a pattern oftrenches and via openings according to the pattern of the masking layer1910′ into the target ILD layer 1908, thereby providing patterned targetILD layer 1908′. The trenches and via openings 2802 define the routingof the metallization layers and/or vias of a layer of the MLI structureof device 1800. Thus, the trenches and via openings 2802 aresubsequently filled with conductive material to provide interconnects2902 of FIGS. 29A and 29B. The interconnects 2902 may include copper,aluminum, alloys, and/or other suitable conductive materials. Theinterconnects 2902 may include a multi-layer structure includes barrierlayers, seed layers, liner layers, and the like. Exemplary barrierlayers include titanium, titanium nitride, tantalum, tantalum nitride,or other alternatives. After deposition of the conductive material,various processes such as a planarization process (e.g., CMP) may beformed.

Thus, the series of FIGS. 19-29B provide for an exemplary implementationof the method 100. As illustrated, the method 100 can be implementedmultiple times in order to pattern a single target layer. The propertiesof the multi-layer patterning stack 604 can provide, in someimplementations, an improvement of pattern quality. For example, LWRand/or LCDU may be improved for the patterned silicon-containing layer(and in some embodiments, the patterned carbon-containing layer), whichallows for improved fidelity of the reproduction of the pattern. Whilenot wanting to be constrained to any theory, it is believed that thedeposition processes and/or material composition of the multi-layerpatterning stack can provide for material properties that allow forimproved performance in the patterning process such as increaseddensity, hardness, desired modulus or high etch selectivity.

FIG. 30 illustrates a fabrication tool 3000 that may be used to performone of more steps of the methods discussed herein. In an embodiment, thefabrication tool 3000 is a chemical vapor deposition tool. In anembodiment, the fabrication tool 3000 is an atomic layer depositiontool. In an embodiment, the fabrication tool 3000 is a physical vapordeposition tool. In particular, the fabrication tool 3000 may be used todeposit the silicon-containing layer as discussed above. In someembodiments, the fabrication tool 300 may further be used to deposit thecarbon-containing layer. In some implementations, precursors in gaseousform are provided to the chamber 3002. Between an upper cathode and alower cathode, a semiconductor structure such as the semiconductorstructure 202 is provided. The semiconductor structure 202 may be in theform of a wafer. An RF power is provided to the upper electrode. Theheat, pressure and/or power or plasma-creation applied to the chamber3002 may assist in the reaction of precursor gases. The reaction createsa layer on the structure 202. As discussed above, in someimplementations, this layer is an amorphous silicon layer.

FIG. 30 illustrates an exemplary precursor to forming asilicon-containing layer including silane. This precursor enters thechamber as is disassociated into silicon and hydrogen, which are theneither deposited or outgassed from the chamber 3002.

In one exemplary aspect, the present disclosure is directed to a methodfor lithography patterning. The method includes providing a substrateand forming a target layer over the substrate. A patterning layer isformed by depositing a first layer having an organic composition;depositing a second layer including over 50 atomic percent of silicon;and depositing a photosensitive layer on the second layer.

In an embodiment, the target layer is an interlayer dielectric (ILD)layer formed over the substrate. In a further embodiment, the methodincludes defining a metallization layer to be formed in the ILD layer.In an embodiment, depositing the second layer is performed by chemicalvapor deposition (CVD), atomic layer deposition (ALD), or physical vapordeposition (PVD). In a further embodiment, depositing the photosensitivelayer is performed by spin-on coating. In an embodiment, depositing thesecond layer includes forming an amorphous silicon (a-Si) layer. Theamorphous silicon layer may be hydrogenated a-Si.

In an embodiment, depositing the first layer includes depositing aspin-on anti-reflective coating layer. In an embodiment, depositing thefirst layer includes depositing amorphous carbon. In a furtherembodiment, the amorphous carbon is deposited by at least one of atomiclayer deposition (ALD), physical vapor deposition (PVD), or chemicalvapor deposition (CVD). In an implementation of the method, an adhesionlayer is deposited between the second layer and the photosensitivelayer.

In another exemplary aspect, the present disclosure is directed a methodfor lithography patterning including providing a target layer. A organicbottom layer of a multi-layer patterning stack is deposited. Asilicon-containing layer of the multi-layer patterning stack is formedover the organic bottom layer using a deposition process providing ofprecursors delivered toward a surface of the organic bottom layer andchemically modifying the precursors to obtain the silicon-containinglayer on the surface. The silicon-containing layer has at least 50%silicon. A resist layer is formed over the silicon-containing layer. Aportion of the resist layer is exposed to a radiation to provide apatterned resist layer. A portion of the silicon-containing layeruncovered by the patterned resist layer is etched to form a patternedsilicon-containing layer. After etching the portion of the siliconcontaining layer, a portion of the organic bottom layer uncovered by thepatterned silicon-containing layer is etched to form a patterned organicbottom layer. The patterned bottom organic layer is used to define apattern in the target layer.

In an embodiment of the method, the deposition process is chemical vapordeposition (CVD) or physical vapor deposition (PVD). In animplementation of the method, the patterned bottom organic layer istrimmed prior to using the patterned bottom organic layer to define thepattern. In an embodiment, the radiation is at an extreme ultraviolet(EUV) wavelength.

In another exemplary aspect, the present disclosure is directed to amethod of patterning a semiconductor device. The method includesdepositing a carbon-containing layer over a substrate. An amorphoussilicon layer is deposited directly on the carbon-containing layer. Aphotosensitive layer is spin coated over the amorphous silicon layer.Using a lithography process, the photosensitive layer is patterned toprovide a first opening. The method continues to include etching theamorphous silicon layer through the first opening where the etchedamorphous silicon layer is used as a masking element during an etchingof the deposited carbon-containing layer.

In an embodiment of the method, depositing the carbon-containing layerincludes forming amorphous carbon. In an embodiment, depositing theamorphous silicon layer includes chemical vapor deposition, atomic layerdeposition, or physical vapor deposition. In an embodiment, etching theamorphous silicon layer introduces atoms from an etching gas into theamorphous silicon layer to form a transformed silicon layer. In someimplementations, the introduced atoms are oxygen.

The foregoing outlines features of several embodiments so that those ofordinary skill in the art may better understand the aspects of thepresent disclosure. Those of ordinary skill in the art should appreciatethat they may readily use the present disclosure as a basis fordesigning or modifying other processes and structures for carrying outthe same purposes and/or achieving the same advantages of theembodiments introduced herein. Those of ordinary skill in the art shouldalso realize that such equivalent constructions do not depart from thespirit and scope of the present disclosure, and that they may makevarious changes, substitutions, and alterations herein without departingfrom the spirit and scope of the present disclosure.

What is claimed is:
 1. A method for lithography patterning, comprising:providing a substrate; forming a target layer over the substrate;forming a patterning layer over the target layer, wherein the formingthe patterning layer, includes: using atomic layer deposition (ALD)process to deposit a first layer having an organic composition;continuing the ALD process to deposit a second layer including over 50atomic percent of silicon, the second layer deposited directly on thefirst layer, and during the ALD process, delivering precursors to thesubstrate to form a continuous variation in a carbon (C) to silicon (Si)ratio in the first layer and the second layer; and depositing apatterning layer on the second layer.
 2. The method of claim 1, whereinthe target layer includes an interlayer dielectric (ILD) layer formedover the substrate.
 3. The method of claim 2, wherein the patterninglayer defines a metallization layer to be formed in the ILD layer; andrecessing an upper surface of the second layer to form a curvilinearupper surface extending between features of the patterning layer.
 4. Themethod of claim 3, further comprising: trimming a width of the secondlayer after the recessing the upper surface of the second layer to froma curvilinear upper surface.
 5. The method of claim 1, furthercomprising: using the deposited patterning layer to define a metalinterconnect line pattern in the target layer.
 6. The method of claim 1,wherein the depositing the second layer includes forming an amorphoussilicon (a-Si) layer.
 7. The method of claim 6, wherein the depositingthe first layer includes depositing amorphous carbon.
 8. The method ofclaim 1, further comprising: depositing an adhesion layer between thesecond layer and the patterning layer.
 9. A method for lithographypatterning, comprising: depositing an organic bottom layer over amasking layer disposed over a target layer; forming a silicon-containinglayer over the organic bottom layer using a deposition process providingof precursors delivered toward a surface of the organic bottom layer andchemically modifying the precursors to obtain the silicon-containinglayer on the surface, wherein the silicon-containing layer has at least50% silicon; forming a patterned resist layer over thesilicon-containing layer, the patterned resist layer including a firstresist feature; performing a first etching process to decrease a heightof the first resist feature and etch an upper surface of thesilicon-containing layer to form a curvilinear surface; after performingthe first etching process, performing a second etching process of thesilicon-containing layer to form a first masking feature of thesilicon-containing layer having tapered sidewalls and a second maskingfeature of the silicon-containing layer having tapered sidewalls,wherein an opening extends between the tapered sidewalls of the firstand second masking features; after the second etching process,performing a third etching process of the organic bottom layer under theopening the second etching process reducing a height of thesilicon-containing layer; and forming interconnect features according toa pattern defined in the organic bottom layer.
 10. The method of claim9, further comprising: reducing a width of the patterned bottom organiclayer prior to forming interconnect features.
 11. The method of claim 9,wherein the first etching process includes introducing oxygen atoms. 12.The method of claim 11, wherein the second etching process includesintroducing oxygen atoms in a dry etching process.
 13. The method ofclaim 9, wherein the patterned resist layer is formed directly on thesilicon-containing layer.
 14. A method for lithography patterning,comprising: depositing a layer over a substrate; forming a plurality offeatures extending from the layer; forming a patterning layer over thelayer and the plurality of features, wherein the forming the patterninglayer, includes: using atomic layer deposition (ALD) process to deposita first layer having an organic composition interfacing a sidewall of afirst feature of the plurality of features; continuing the ALD processto deposit a second layer including over 50 atomic percent of silicon,wherein the depositing the first layer and the depositing the secondlayer are performed in-situ, and during the ALD process, deliveringprecursors to the substrate to form a continuous variation in a carbon(C) to silicon (Si) ratio in the first layer and the second layer; anddepositing a photosensitive layer over the second layer.
 15. The methodof claim 14, wherein the plurality of features are mandrels.
 16. Themethod of claim 15, wherein a height of the first layer is about 1.2 to4 times a height of the plurality of features.
 17. The method of claim14, wherein forming the plurality of features includes forming featurescomprising silicon.
 18. The method of claim 14, wherein the depositingthe first layer and the depositing the second layer is performed at roomtemperature.
 19. The method of claim 14, further comprising: etching thesecond layer, wherein after the etching a first thickness of the secondlayer remains and a second thickness of the first layer remains, whereina ratio of the first thickness to the second thickness is between 2:1and 10:1.
 20. The method of claim 14 wherein the forming the pluralityof features includes forming a first feature and a second feature with agap extending between the first feature and the second feature, whereinthe first layer completely fills the gap.